Have no idea what this is. Any help offered is greatly appreciated. Thanks.

I'm the proud owner of a beautiful 2005 Volvo S80 T6 with around 151k. A little earlier today I was looking around for the canister purge valve, which I still haven't found, and I saw this (see the red arrow). After looking around for a part number, I've decided to turn to the forums for help. Can someone tell me what this is please? Thank you.

 

Random searches on the internet for the win! This is a brake booster vacuum switch (31400692). Thanks anyway.